Correlation between MMP and TIMP levels and elastic moduli of ascending thoracic aortic aneurysms.

Objective: The objective of this preliminary investigation is to determine if there is a relation between the biological levels of matrix metalloproteinases and tissue inhibitor of matrix metalloproteinase (TIMP) and the elastic moduli of the ascending aortic wall in patients with ascending thoracic aortic aneurysms (ATAA).

Methods: Circumferential specimens from twelve patients with ATAA were obtained from the greater curvature and their tensile properties (maximum elastic modulus) were tested uniaxially. The levels of MMP1, 2, 3, 8, and 9 as well as TIMP1 and 2 were determined in these aortic wall specimens using MMP/TIMP antibodies array.

Results: Direct relations were found between MMP2 and the elastic modulus of the ascending aorta wall (R = 0.52) and between MMP9 and TIMP1 (R = 0.63). However, weak positive relation was found between MMP2 and TIMP2 (R = 0.23). We found inverse relations between MMP3 and MMP8 levels and the elastic module. There were no relations between MMP1 and MMP9 levels and the elastic modulus of aortic wall.

Conclusions: This preliminary study looks at the relationship between the elastic modulii and the MMPs/TIMPs levels found in aortic wall specimens. Given that the value of the elastic moduli can be obtained non-invasively, a close relation might permit to infer the value of MMPs and TIMPs levels from the non-invasive determination of the elasticity of the aortic wall. By allowing the non-invasive determination of the mechanical and biological properties of the aorta in in-vivo, the method proposed here might improve the prediction of outcomes of ascending aortic aneurysms. This is a very preliminary study (small sample size) and the outcomes of this study cannot be used as final conclusions and should be verified in further studies with larger sample of patients.